* No new substances are formed: When butter melts, it changes from a solid to a liquid, but it's still composed of the same molecules (fat, water, milk solids). The chemical makeup hasn't changed.

* The change is reversible: You can easily solidify melted butter again by cooling it down.

* The change is due to a change in state: Melting is simply a change in the physical state of matter, from solid to liquid.

In contrast, a chemical change would involve:

* The formation of new substances with different properties.

* The breaking and forming of chemical bonds.

* The change is often irreversible or difficult to reverse.

Let me know if you have any other questions!